Often apparatus and methods are used to add a concentrate to a diluent in order to create an effective use solution. Diluting a concentrate with water flowing in a water line is one example. Using an active ingredient in concentrated form and relying on-site dilution of the active ingredient allows more efficient use of shipping and storage of the active ingredient. The volume and weight of the water diluent need not be shipped to the point of usage nor stored at the point of usage.
In the cleaning environment, it is common to dilute a concentrate of a sanitizer or cleaner on-site with locally supplied water. Apparatus and methods are commonly used to dilute the concentrated sanitizer or cleaner, for example, to form a commercially suitable use solution.
Aspirators are commonly used for this purpose. An aspirator is essentially a pipe (the water line) with a narrowing in it. As water flows through that narrowing, the velocity of the water increases and the water pressure drops. An opening on the side of line is connected to a hose which, in turn, is connected to the concentrate. Since the water pressure in the high speed water flow is lower than atmospheric pressure, atmospheric pressure pushes the concentrate through the connected tube into the water flowing through the line.
Such aspirators work well to add concentrate to water flowing in a line at certain amounts of dilution. At dilution rates down to approximately 1:130 (that is, a dilution rate of one part concentrate to 130 parts diluent), the amount of concentrate being added to the water diluent can be controlled by varying the size of the opening on the side of the line. Making the opening larger increases the amount of concentrate added to the line. Making the opening smaller decreases the amount of concentrate added to the line.
However, at dilution rates lower than approximately 1:130 (that is, one part concentrate to more than 130 parts diluent), it is difficult to control the amount of concentrate added to the line by simply varying the size of the opening in the side of the line. At low dilution rates, i.e., small amounts of concentrate added to the line, variations in the water pressure, flow rate, temperature of the water can all result in significant variations in the amount of concentrate added to the water (diluent) in the line. Further, it is easy to plug the opening into the line with foreign material limiting the amount of concentrate which is added to the diluent flowing in the line or completely eliminating any concentrate to the line. Thus, it is difficult to accurately use an aspirator to add concentrate to a diluent flowing in a line with the use of an aspirator.
However, many applications require just such low dilution rates. An example is the addition of a sanitizer to form a use solution for a warewashing application. If highly concentrated sanitizer is utilized, dilution rates of approximately one part in one hundred thirty to one part in one hundred fifty or less may be desired. An aspirator is often unreliable and unworkable in this situation.
Thus, there is needed an apparatus and method to accurately control the addition of a concentrate to a diluent flowing in a line at dilution rates not more than 1:130.